基于IDA法的矩形地下车站层间位移角抗震性能限值研究

Study on Seismic Performance Limit Value of Story Drift Angle of Rectangular Underground Station Based on IDA Method

在常用增量动力分析(IDA)法基础上,为了使得IDA法适用于地下结构抗震性能分析,把自由场地震反应和土-结构相互作用反应分开进行;首先采用等效线性化进行一维自由场分析,得到反应加速度法所需的土层加速度法,然后采用反应加速度法进行土-结构相互作用分析;上述两步计算理论成熟,计算工作量小,因此修正的IDA法计算效率高。选取结构形式、场地类别、地震波、土层厚度、结构埋深等5个影响地下车站抗震性能的因素,通过正交试验设计,设置25个工况;采用修正IDA法进行增量动力分析,以地震动时程加速度峰值作为地震动强度参数(IM),以层间位移角作为结构性能参数(DM),得到25条IDA曲线。根据屈服点和倒塌点的定义,在每条IDA曲线上得到屈服点和倒塌点的层间位移角数值,通过对25个工况结果的数值平均,得到钢筋混凝土矩形地下车站层间位移角屈服点和倒塌点限值分别为1/482和1/25。通过对25个工况结果的极差分析,得到5个影响因素的主次顺序,屈服点和倒塌点影响因素的主次顺序不尽相同。

Based on original incremental dynamic analysis(IDA),modified IDA was proposed in order to be appropriate for seismic performance analysis of underground structures,that was being solved in two steps.Firstly,free field analysis was analyzed by equivalent linear method,and then each layer of soil acceleration was provided to subsequent response acceleration method.Secondly,soil-structure interaction was analyzed through response acceleration method.Above mentioned two methods are maturational theories,whose computation is small and the efficient is high.Twenty five working conditions were set up by means of orthogonal experimental design,whose factors were five and factor levels were five.Five factors respectively were structure type,site classification,seismic wave,soil thickness and burial depth.Twenty five IDA curves were calculated through modified IDA,whose ground motion intensity measure(IM)was PGA(peak ground acceleration)and structure damage measure(DM)was story drift angle.Story drift angles for yield point and collapse point were gotten from twenty five IDA curves based on definition of yield point and collapse point.Then seismic performance limit values of story drift angle of rectangular underground station were 1/482(yield point)and 1/25(collapse point)by average of above twenty five data.The extents of influence of five factors on seismic performance are sorted through range analysis for above twenty five data.And the order of factors on yield point and collapse point is different.